A lot of users have this problem so I thought the fix for it would be appreciated, creds to the guy that came up with this, here's the original thread: http://forums.steampowered.com/forums/showthread.php?t=1043281
So here's how you do it, open accessories and click run, type "regedit" and run it.
Next expand HKEY_LOCAL_MACHINE -> SOFTWARE -> Microsoft -> Windows NT -> CurrentVersion -> Multimedia -> SystemProfile
Open the entry called "NetworkThrottlingIndex" and set the value data to "ffffffff" and Reboot, now you can play normally again! Also be careful when you're messing with your registry.
Copiado y pegado de http://forums.heroesofnewerth.com/showthread.php?t=168157
estoy testeandolo ahora, a ver si funciona bien